Sure, I think the power button on the bottom sucks, but power buttons on the Mini and Studio have sucked for a long time...
True - the button on the Studio - contoured flush into a corner (I think the M2 Mini was similar) - is a perfect storm of fiddly to find when you need it and possible to press accidentally. That said, somehow I've never contrived to press it accidentally when plugging stuff in or moving it - plus it needs a long press to power off - and as for accidentally switching on, there are other good reasons for not moving the Mini when you have it plugged in to power and other devices which might not appreciate having their cables jerked out, but, yeah, it had already been hit with the "form over function" stick.
Unfortunately, rather than address those issues (like, combine it with the front power LED as many here have suggested, or needing a long press to power
on, as per iDevices) Apple decided to double down on their "let's prevent that power button offending users' eyes" obsession and hide it in an even less convenient place.
To be fair, it
is now harder to accidentally press the power button when you have to pick your Mac up... in order to press the power button. Oh, wait...

(And, seriously, that button is right where your fingers are going to go if you pick the Mac up).
I actually think the button on the bottom might be a bit BETTER for this, as it will be mechanically simpler and more reliable to constructy a mechanism for this than for pushing a button from the back.
Mechanically, unless you mount the mechanical button on the bottom of the rack, you still need some sort of lever/cam/widget to rotate the force of the press through 90 or 180 degrees - OK, hardly rocket surgery but no simpler than putting a remote button on the front of a rack.
What you actually want is an Arduino operating a servo so you can have proper lights-out remote management!
Of course, if Apple would come up with a simple solution for a remote start button or - gasp! - just put the darn button on the front, it would be 1000 times better.
In terms of rack mount, the issue is why the 4th largest PC maker can't - maybe in collaboration with Sonnet or somebody - make a proper rackmount Mx Pro/Max system with the usual server trimmings of modular/redundant power supplies, lights out management etc. Sure, it would be a niche product, there wouldn't be stock in the Apple store in Liechtenstein - but it could probably be done with a standard Mac Studio logic board (which I believe has most of the ports etc. on daughterboards) and the sort of custom heat-sinks and enclosures that even relatively tiny PC OEMs seem to manage to source...
Of course - they
used to - the XServe - but I think that kinda lost its Unique Selling Point when Apple switched to Intel and the XServe became a.n.other rackmount PC running what is - for server purposes - Unix. Now they have their own unique CPU -
plus an army of developers needing to build apps for A-series/M-series chips with rapidly converging MacOS/iOS frameworks etc. - it may have a role again.
Instead, they have very cleverly made the new Mini smaller in width and depth but
too tall to fit in a 1U rack, moved some ports to the front edge and moved both the air intake and outlet to the base (so rack mount makers are going to have to be careful not to trap the hot air and feed it back into the intake...)
These Minis do offer fantastic bangs-per-buck (except the 256GB SD models) but design-wise they're a superficially cute form-over-function dumpster fire.
It will be interesting to see how the "honest" reviews rate the thermals/noise - but it's simple physics that cooling relies on a combination of surface area and what volume of air per second you can shift through the heatsinks. Surface area goes down with the
cube of physical dimensions, while smaller fans, smaller air ducts, smaller heat sinks mean the air has to move faster to shift the same volume, which tends to create more noise. Maybe Apple have cracked this with clever engineering (hopefully the cooling wasn't designed by the genius who came up with the power button) but they've made things harder for themselves with their "smaller is better" obsession.
I just hope that, for the M4 Mac Studio, they de-prioritise size vs. functionality.